Bypass conduits for reducing thermal fatigue and stress in heat recovery steam generators of combined cycle power plant systems

Abstract

Heat recovery steam generators (HRSGs) including bypass conduits for reducing fatigue and/or stress experienced by components within the HRSGs are disclosed. The HRSG may include a steam generator module generating steam, and a first superheater module positioned downstream of the steam generator module. The first superheater module may receive the steam generated by the steam generator module. The HRSG may also include a second superheater module positioned downstream from the first superheater module, and a bypass conduit for receiving a portion of the steam generated by the steam generator module. The bypass conduit may include an inlet positioned downstream of the steam generator module, and an outlet positioned downstream of the first superheater module. Additionally, the HRSG may include a valve in fluid communication with the bypass conduit to provide steam to the outlet of the bypass conduit.

What is claimed is: 
     
       1. A heat recovery steam generator (HRSG) for a combined cycle power plant system, the HRSG comprising:
 a steam generator module generating steam; 
 a first superheater module positioned downstream of the steam generator module, the first superheater module receiving the steam generated by the steam generator module; 
 a second superheater module positioned downstream from the first superheater module; 
 a header positioned downstream of and in fluid communication with the second superheater module; 
 a bypass conduit for receiving a portion of the steam generated by the steam generator module, the bypass conduit including:
 an inlet positioned downstream of the steam generator module, and 
 an outlet positioned downstream of the first superheater module, the outlet in direct fluid communication with the header; and 
 
 a valve in fluid communication with the bypass conduit, the valve providing steam to the outlet of the bypass conduit. 
 
     
     
       2. The HRSG of  claim 1 , wherein the inlet is positioned between the steam generator module and the first superheater module. 
     
     
       3. The HRSG of  claim 2 , wherein the valve is positioned at one of:
 the inlet of the bypass conduit, between the steam generator module and the first superheater module, or 
 directly on the bypass conduit, between the inlet and the outlet. 
 
     
     
       4. The HRSG of  claim 2 , further comprising:
 an outlet manifold positioned downstream of and in fluid communication with the header. 
 
     
     
       5. The HRSG of  claim 2 , wherein the outlet of the bypass conduit is positioned between the first superheater module and the second superheater module. 
     
     
       6. The HRSG of  claim 5 , further comprising:
 a desuperheater module including an inlet positioned between the first superheater module and the second superheater module, the inlet of the desuperheater module positioned upstream of the outlet of the bypass conduit. 
 
     
     
       7. The HRSG of  claim 1 , wherein the valve provides steam to the outlet of the bypass conduit based on an operational characteristic, the operational characteristic including at least one of:
 a temperature of a header positioned downstream of and in fluid communication with the second superheater module; 
 a temperature of an outlet manifold positioned downstream of and in fluid communication with the header; 
 a temperature of the steam generated by the steam generator module; 
 a temperature of the steam after flowing through the first superheater module; 
 a temperature of the steam after flowing through the second superheater module; 
 a duration of operation of the steam generator module; 
 a temperature of an exhaust gas flowing over the first superheater module and the second superheater module; or 
 a steam flow measurement of the steam. 
 
     
     
       8. The HRSG of  claim 7 , further comprising:
 a controller operatively coupled to the valve to adjust the position of the valve between an open position and a closed position to provide steam to the outlet of the bypass conduit based on the operational characteristic and 
 at least one sensor operatively coupled to the controller to detect the operational characteristic. 
 
     
     
       9. A combined cycle power plant system comprising:
 a gas turbine system including a turbine component discharging an exhaust gas; and 
 a heat recovery steam generator (HRSG) in fluid communication with the turbine component for receiving the exhaust gas, the HRSG including:
 a steam generator module generating steam; 
 a first superheater module positioned downstream of the steam generator module, the first superheater module receiving the steam generated by the steam generator module; 
 a second superheater module positioned downstream from the first superheater module; 
 a header positioned downstream of and in fluid communication with the second superheater module; 
 a bypass conduit for receiving a portion of the steam generated by the steam generator module, the bypass conduit including:
 an inlet positioned downstream of the steam generator module; and 
 an outlet positioned downstream of the first superheater module, the outlet in direct fluid communication with the header; and 
 
 a valve in fluid communication with the bypass conduit, the valve providing steam to the outlet of the bypass conduit. 
 
 
     
     
       10. The combined cycle power plant system of  claim 9 , wherein the inlet of the bypass conduit of the HRSG is positioned between the steam generator module and the first superheater module of the HRSG. 
     
     
       11. The combined cycle power plant system of  claim 10 , wherein the HRSG further comprises:
 an outlet manifold positioned downstream of and in fluid communication with the header. 
 
     
     
       12. The combined cycle power plant system of  claim 10 , wherein the outlet of the bypass conduit of the HRSG is positioned between the first superheater module and the second superheater module of the HRSG. 
     
     
       13. The combined cycle power plant system of  claim 12 , wherein the HRSG further comprises:
 a desuperheater module including an inlet positioned between the first superheater module and the second superheater module, the inlet of the desuperheater module positioned upstream of the outlet of the bypass conduit. 
 
     
     
       14. A heat recovery steam generator (HRSG) for a combined cycle power plant system, the HRSG comprising:
 a steam generator module generating steam; 
 a first superheater module positioned downstream of the steam generator module, the first superheater module receiving the steam generated by the steam generator module; 
 a second superheater module positioned downstream from the first superheater module; 
 a header positioned downstream of and in fluid communication with the second superheater module; 
 a bypass conduit for receiving a portion of the steam generated by the steam generator module, the bypass conduit including:
 an inlet positioned downstream of the steam generator module, between the first superheater module and the second superheater module, and 
 an outlet positioned downstream of the first superheater module, the outlet in direct fluid communication with the header; and 
 
 a valve in fluid communication with the bypass conduit, the valve providing steam to the outlet of the bypass conduit. 
 
     
     
       15. The HRSG of  claim 14 , wherein the valve is positioned at one of:
 the inlet of the bypass conduit, between the first superheater module and the second super heater module, or 
 directly on the bypass conduit, between the inlet and the outlet. 
 
     
     
       16. The HRSG of  claim 14 , further comprising:
 an outlet manifold positioned downstream of and in fluid communication with the header; 
 a steam supply conduit in fluid communication with and positioned downstream of the outlet manifold; and 
 a distinct bypass conduit including:
 a distinct bypass inlet positioned downstream of the first superheater module; and 
 a distinct bypass outlet in direct fluid communication with the steam supply conduit, downstream of the outlet manifold.